TY - JOUR
T1 - 5-Hydroxytryptamine stimulates fluid secretion in locust malpighian tubules independently of cAMP
AU - Morgan, Peter J.
AU - Mordue, William
PY - 1984/1/1
Y1 - 1984/1/1
N2 - 1. 5-Hydroxytryptamine (5-HT) stimulates fluid secretion by semi-isolated Malpighian tubules of Locusta in a dose-dependent manner. 2. The threshold of stimulation is between 10-8 and 10-7 M 5-HT; maximal activation occurs at doses greater than 10-6 M. 3. Relative to the activation induced by diuretic hormone (storage lobe extracts), 5-HT increases the rate of fluid secretion by only 65%. 4. Phentolamine, the α-adrenergic blocker, failed to inhibit either DH or 5-HT stimulated secretion. 5. Diuretic hormone raises the levels of intracellular of cAMP, and activates adenylate cyclase in plasma membrane preparations of Locusta Malpighian tubules. 6. 5-HT (10-4 M) has no effect in either assay system. 7. Thus 5-HT can stimulate fluid secretion independently of cAMP. 8. A hypothetical model for hormone stimulated fluid secretion by Locusta Malpighian tubules, involving dual-receptor activation, is proposed. 9. Other biogenic amines, including octopamine, adrenalin, dopamine, synephrine and the formamidine chlordimeform were tested for their ability to stimulate fluid secretion. 10. Only dopamine showed a weakly stimulatory effect.
AB - 1. 5-Hydroxytryptamine (5-HT) stimulates fluid secretion by semi-isolated Malpighian tubules of Locusta in a dose-dependent manner. 2. The threshold of stimulation is between 10-8 and 10-7 M 5-HT; maximal activation occurs at doses greater than 10-6 M. 3. Relative to the activation induced by diuretic hormone (storage lobe extracts), 5-HT increases the rate of fluid secretion by only 65%. 4. Phentolamine, the α-adrenergic blocker, failed to inhibit either DH or 5-HT stimulated secretion. 5. Diuretic hormone raises the levels of intracellular of cAMP, and activates adenylate cyclase in plasma membrane preparations of Locusta Malpighian tubules. 6. 5-HT (10-4 M) has no effect in either assay system. 7. Thus 5-HT can stimulate fluid secretion independently of cAMP. 8. A hypothetical model for hormone stimulated fluid secretion by Locusta Malpighian tubules, involving dual-receptor activation, is proposed. 9. Other biogenic amines, including octopamine, adrenalin, dopamine, synephrine and the formamidine chlordimeform were tested for their ability to stimulate fluid secretion. 10. Only dopamine showed a weakly stimulatory effect.
UR - http://www.scopus.com/inward/record.url?scp=0021690593&partnerID=8YFLogxK
U2 - 10.1016/0742-8413(84)90205-6
DO - 10.1016/0742-8413(84)90205-6
M3 - Article
C2 - 6151458
AN - SCOPUS:0021690593
SN - 0306-4492
VL - 79
SP - 305
EP - 310
JO - Comparative Biochemistry and Physiology. Part C, Comparative
JF - Comparative Biochemistry and Physiology. Part C, Comparative
IS - 2
ER -